Transcript for Man Was Trying to Save Himself When He Breached JFK Airport Runway

Now, to a stunning story about a major breach at one of the country's busiest airports. A young man in swim trunks and a life vest, walking right on to the runway at jfk airport, undetected by supposedly sophisticated security. The big question, how did it happen? Well, he talked exclusively to abc's jim avila. Jim? Reporter: Good morning, amy. It is a jaw-dropper. The port authority which runs the airport says it has stepped up patrols since the embarrassing incident. And is working with a security firm to fix the problem. Twice this summer, the intruder, danny, has taken authorities back to show them his route. Danny beat a security system at jfk, one of america's largest airports, without even trying. The whole intention the whole time was to make myself seen. Reporter: It was an august night, aboard danny's just-repaired bright yellow jet ski, when it broke down just off of the airport approach. Through the darkness, all he could see was the control tower. After a three-mile swim a hike through a muddy marsh, cold and disoriented, danny reached a chain-link, barbed wire airport fence. And the moment of truth. Climb it and violate the law? Or sit there and risk death. I made a decision. I'm going to have to get found. Reporter: Danny climbed the fence. Nothing happened. The tower was my landmark. That was the only thing lit up i could go to. Reporter: Across taxiways and runways. But nobody saw him. And the motion detectors and cameras that the airport paid millions for, didn't pick him up. You were trying to use the security. I was thinking I would be on camera. Somebody would pick me up. Maybe a helicopter would come or a police car, something. Nothing happened, to the point where I had to walk up to a cargo worker. I had to walk up to a cargo worker. Reporter: In the end, danny was arrested and charged with felony trespass, finally pleading guilty to a misdemeanor. The only one to pay for a startling breakdown? Security. You could have walked to an airplane. Exactly. Reporter: Are you, as a s.I.D.S., Concerned about that? Very concerned about that. I didn't mean to do this. But I exposed something really important. And that's a flaw in security. Reporter: Danny's now suing the port authority for his treatment after he turned himself in to a delta worker. He said he was questioned for hours without offer of warm clothes, medical treatment or food. The port authority has not responded to those charges yet. And a misdemeano conviction, no less, as well. It's on his record. He had to pay for attorneys. A lot of things happened there on a very bad night for danny. Jim avila, thanks so much.

This transcript has been automatically generated and may not be 100% accurate.

Murder Suspect Steals Unlocked Passenger Jet, Crashes

The fugitive pilot killed himself after crashing the plane in a nearby parking lot.

San Diego Airport Security Breach

A man was able to board a plane without a ticket.

{"id":17551248,"title":"Man Was Trying to Save Himself When He Breached JFK Airport Runway","duration":"3:00","description":"Danny Casillo exposed flaws in a multimillion-dollar security system without even trying.","section":"GMA","mediaType":"Default"}